The present invention relates to a temperature regulating device, for use on electrical household appliances, consisting of a temperature sensor which generates an electrical quantity depending on the temperature it is at, a signal translating circuit for processing the electrical quantity and producing a control signal and a regulating element which receives the control signal and acts accordingly on the appliance components on which temperature adjustment depends.
A device of the type described could be used, for example, on: refrigerators, ovens and washing machines.
Two different types of temperature regulator are currently used on these appliances: electromechanical and solidstate electronic regulators, both of which have drawbacks. The problems associated with the first type are typical of any electromechanical device: moving parts wear out in time to produce a fall in efficiency until the device actually breaks down; fine adjustment of component operation is difficult unless high-cost products are used; flexibility of the device is low if alterations prove necessary for improving machine operation.
Though none of these problems is found on electronic regulators, they have other drawbacks mainly due to the fact that they have only recently been applied to the household appliances mentioned above and there has not been sufficient time as yet for their application to be optimized. The major problem associated with solid-state regulators is correct control of the regulating element. This usually consists of a triac and the difficulty lies in the fact that it must receive the firing signal at precise times if it is to operate in such a way as to guarantee a long working life.
Further difficulty is encountered in handling the signal from the temperature sensor so as to ensure proper intervention of the heat regulating circuit under all operating conditions.